Refer to FIG. 1 for a conventional guide connector that connects two circuit boards to meet multiple functional requirements of a programmable logic controller. The programmable logic controller usually has a plurality of circuit boards 400 to execute different operational requirements. A connector 500 is provided to connect two circuit boards 400 to transmit signals there between.
The conventional connector 500 consists of metal transmission lines 501 and two anchor docks 502. The metal transmission lines 501 have two free ends, inserting respectively into insert holes 402, formed on the two circuit boards 400 for transmitting signals there between. The two anchor docks 502 couple and hold the metal transmission lines 501 to maintain the relative coupling positions.
The structure set forth above has drawbacks, notably:
First, the diameters of the metal transmission line 501 and insert holes 402 on the circuit boards 400 are very small. During assembly on production lines in large number, it tends to occur that the metal transmission lines 501 do not completely align with the insert holes 402 because of equipment deviations and tolerances. This results in damage of the metal transmission lines 501 or circuit boards 400 and causes drop of production  yield.
Second, connection of the connector 500 and the circuit boards 400 solely relies on coupling of the metal transmission lines 501 and the insert holes 402. This is not a reliable structure. The connector 500 is easily damaged because of external shaking. As a result, signal transmission in the programmable logic controller will be affected.
Third, the conventional connector 500 is a fixed apparatus. If the distance between two circuit boards 400 is shrunk, the original connector 500 becomes useless, and a new one has to be fabricated. This results in additional costs and waste of resources.